Dear Uddipto Chakraborty,
Thanks for your concern,
Photograph with glasses is not acceptable at the airport.
However you can take photo once you arrive Vietnam.
Prepare 2 photos 4x6 cm (or same size passport photos) . If you don’t have photos, You can take photos at the airport when you arrive and it costs 5USD/person in HCM. ( or 2 USD/person in Hanoi).
Stepfanno Tran (Mr. )